JPH02206654A - Room temperature curing organopolysiloxane composition - Google Patents

Abstract

PURPOSE:To obtain the title composition suitable as adhesive for electrical and electronic parts, having excellent shelf stability and curing properties by blending a specific diorganopolysiloxane with specific amounts of a filler, alkoxysilane (partial hydrolyzate), etc. CONSTITUTION:(A) 100 pts.wt. diorganopolysiloxane containing both ends of molecular chain hindered with hydroxyl group or di or trialkoxy group is blended with (R) 1-400 pts.wt., preferably 5-200 pts.wt. filler (e.g. fine power silica or silica aerogel), (C) 1-50 pts.wt. alkoxysilane shown by formula I (R<1> is monofunctional hydrocarbon; R<2> is alkyl; m is 0 or 1) or partial hydrolyzate thereof, (D) 0.01-10 pts.wt. silane or siloxane containing one or more groups shown by formula II (R<3> is H or monofunctional hydrocarbon) in one molecule, (E) 0.01-10 pts.wt. organotin compound and (F) 0.5-10 pts.wt. organopolysiloxane containing one or more alkenyloxy groups.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a room-temperature-curable organopolysiloxane composition, particularly a dealcoholization-type room-temperature-curable organopolysiloxane composition with excellent storage stability. .

[Prior Art] Various types of room-temperature curable organopolysiloxane compositions are known. Compositions containing catalysts such as organic titanium chelate compounds generate alcohol during curing to form rubber-like surganoborisiloxane, so they are non-corrosive and do not emit irritating odors. It is widely used as an adhesive in industry.

However, this type of dealcoholization-type room-temperature-curable organopolysiloxane composition (hereinafter abbreviated as RTV siloxane composition) generally has the disadvantages of slow curing speed and poor internal curing properties and poor storage stability. When stored for a long time, it has the disadvantage that it does not harden during use even if it is in an anhydrous state.

Therefore, for this type of composition, a method has been proposed in which a silane compound having a dialkoxy group is used as a so-called silane scavenger to improve its storage stability and curability. It is necessary to newly manufacture the compound, and in order to improve storage stability, replace the hydrolyzable group other than the dialkoxy group of the silane compound with one with high reactivity such as an amide group or amine group. However, since these groups are corrosive and have an odor, they have the disadvantage that they cannot be used as adhesives in the electrical and electronic industries.

In addition, this type of composition is made by adding an alkoxysilane or a partial hydrolyzate thereof, a zyl-substituted alkyl alkoxysilane, and an organotin compound to a diorganopolysiloxane whose molecular chain ends are blocked with a hydroxyl group. A method has also been proposed (Japanese Patent Application Laid-open No. 1983-
52351), which is said to have good storage stability, but in reality it is free alcohol produced by the reaction of the silanol group in diorganopolysiloxane with alkoxysilane or its partial hydrolyzate. However, there is a drawback that the storage stability is extremely poor due to the residual presence of silane in the composition, and it has also been proposed to use an alkenyloxy group-containing alkoxysilane as a hydroxy-based silane scavenger (Japanese Patent Application Laid-Open No. 1989-1992).
-18546, JP-A-60-18547)
However, RT containing such alkenyloxysilane
V-siloxane compositions have the disadvantage that when stored in a sealed container, the color of the composition changes from yellow to brown during storage.

[Structure of the Invention] The present invention relates to a dealcoholization type RTV siloxane composition that solves the above-mentioned disadvantages.
) 100 parts by weight of diorganopolysiloxane whose molecular chain ends are blocked with hydroxyl or di- or trialkoxy groups, 2) 1 to 400 parts by weight of filler, 3) General formula R'mS
l (OR2) a-(where R1 is a monovalent hydrocarbon group,
R2 is an alkyl group or an alkyl group substituted with an alkoxy group,
m is 0 or 1) alkoxysilane or its partial hydrolyzate from 1 to 50! i amount part, 4) general formula (83
2N) 0.01 to 10 parts by weight of silane or siloxane having at least one group represented by 2C-N- (where 83 is a hydrogen atom or a monovalent hydrocarbon group) in one molecule,
5) 0.01-10 parts by weight of an organic tin compound and 6) 0.5-10 parts by weight of an organopolysiloxane containing at least one alkenyloxy group per molecule.

That is, the present inventors conducted various studies on dealcoholization-type RTV siloxane compositions with excellent storage stability that solved the disadvantages described above, and found that the storage stability of conventionally known dealcoholization-type RTV siloxane compositions The reason for poor curability is the low reactivity of the hydroxyl group in organosiloxane which has a hydroxyl group at the end of the molecular chain, and the alkoxy group in the silane compound which has an alkoxy group that should react with the water contained in the filler. It has been found that this is because unreacted silanol groups remain and that free alcohol produced by the reaction between the silane compound having an alkoxy group and the silanol group is present in the composition.

Therefore, the present inventors mixed a filler as a component 2) with the diorganopolysiloxane as a component 1), and then added an alkoxysilane or a partial hydrolyzate thereof as a component 3). When the guanidyl group-containing silane or siloxane as the 4) component and the organotin compound as the 5th component are mixed with air excluded, the process)
Component 2) The silanol groups and water contained in component 3) react with the alkoxysilane or its partial hydrolyzate to eliminate the presence of silanol groups in the mixture, but this composition does not contain alcohol. will remain,
If this alcohol is left as it is, the storage stability of this RTV siloxane composition will deteriorate, so if an organopolysiloxane containing an alkenyloxy group as the component 6) described above is added, the guanidyl group-containing component as the component 4) is added. With silane or siloxane acting as a catalyst, this residual alcohol undergoes an exchange reaction with the alkenyloxy groups of the alkenyloxy group-containing organopolysiloxane, and free alcohol is captured, resulting in virtually no silanol groups or alcohol, and storage stability. Excellent RTV
It has been found that a siloxane composition can be obtained, and that the discoloration after storage that occurs when alkenyloxysilane is used as a scavenger does not occur at all when alkenyloxysiloxane is used. After confirming that an excellent RTV composition can be easily obtained, the present invention was completed by conducting research on the blending ratio of each component used therein, the mixing method, etc.

The diorganopolysiloxane as component 1) constituting the composition of the present invention is considered to be the main ingredient of this composition, and is represented by the average composition formula R,5iO4-, and this R
is an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a 2-ethylbutyl group, an octyl group, a cycloalkyl group such as a cyclohexyl group or a cyclopentyl group,
Flukenyl groups such as vinyl and hexenyl groups, aryl groups such as phenyl, tolyl, xylyl, naphthyl, and diphenyl groups, aralkyl groups such as benzyl and phenylethyl groups, or carbon atoms of these groups. The same or different unsubstituted or substituted 1 selected from chloromethyl group, trifluoropropyl group, 2-cyanoethyl group, 3-cyanopropyl group, etc. in which part or all of the hydrogen atoms are substituted with halogen atoms, cyano groups, etc. The valence hydrocarbon group, a is 1.90 to 2.05, is said to be one in which both ends of the molecular chain are blocked with a hydroxyl group or a di- or trialkoxy group. In order to have good rubber elasticity and excellent mechanical strength, this material must have a viscosity of 25c at 25°C.
S or higher is required.

If necessary, this product may be mixed with diorganopolysiloxane whose molecular chain end is blocked with a group other than a hydroxyl group, di- or trialkoxy group, such as a trimethylsilyl group. It is preferable that the amount is equal to or less than the amount of diorganopolysiloxane whose terminal end is capped with a hydroxyl group, di- or trialkoxy group.

In addition, the filler as component 2) in the composition of the present invention may be a known filler, including finely powdered silica, silica aerogel, precipitated silica, diatomaceous earth, iron oxide, zinc oxide, titanium oxide, and other metals. Oxides or their surfaces treated with silane, metal carbonates such as calcium carbonate, magnesium carbonate, zinc carbonate, asbestos, glass cool, carbon black, fine mica, fused silica powder, polystyrene, polyvinyl chloride, polypropylene, etc. Synthetic resin powder is exemplified, but if the blending amount is less than 1 part by weight per 100 parts by weight of the above-mentioned 1) component, the cured product obtained from this composition will not exhibit sufficient mechanical strength. If the amount exceeds 4001 parts, the viscosity of the room-temperature-curable organopolysiloxane will increase and the workability will deteriorate, and the rubber strength after curing will decrease, making it difficult to obtain the desired rubber elastic body. ~400! The preferred range is 5 to 20 parts.
0 parts by weight.

Next, the alkoxysilane as component 3) in the composition of the present invention is represented by the formula R'-5l(OR')4-, where R' is a methyl group, an ethyl group, a propyl group, a vinyl group,
Monovalent hydrocarbon crystals such as phenyl group and trifluoropropyl group, R2 is an alkyl group such as methyl group, ethyl group, propyl group, butyl group, and alkoxyalkyl group such as methoxyethyl group and ethoxyethyl group. Methylethyltrimethoxysilane, vinyltrimethoxysilane,
Tetraethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, methyltriisopropoxysilane, phenyltrimethoxysilane, phenyltri(methoxyethoxy)silane, vinyltri(methoxyethoxy)silane, tetra(ethoxyethoxy)silane, trifluoropropyl Any material such as trimethoxysilane may be used, but it may also be a siloxane obtained by partially hydrolyzing and condensing these materials.

Note that among the above components, methyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, methyltri(methoxyethoxy)silane, and vinyltri(methoxyethoxy)silane are preferred as component 3), but this combination If the amount is too large, the physical properties of the room-temperature-curable organopolysiloxane composition after curing will be poor in rubber elasticity, and it will also be economically disadvantageous. A range of 50 parts by weight is required.

Next, the silane or siloxane as component 4 in the composition of the present invention has the general formula (R32N) 2C-N-(
R3 has at least one group represented by a hydrogen atom or a monovalent hydrocarbon group in one molecule, which silylates water and silanol in the base compound with the component 3) described above. It sometimes acts as a catalyst.

The above groups may be bonded to the silicon atom through any group, but generally they are preferably bonded to the silicon atom through an alkylene group or an oxyalkylene group. Examples include those shown by the formula (where Me is a methyl group, Et is an ethyl group, Pr is a propyl group, and pH is a phenyl group); Preferably, it is an organosilane. Note that if the amount of component 4) is too small, the effect of promoting the reaction between component 3) and the base compound consisting of component 1) and component 2) described above will be insufficient, and this reaction will last for a long time. However, hydroxyl groups and water remain in the reaction product, making the composition poor in storage stability.On the other hand, if too much of this is present, the reaction speeds up, but the reaction product becomes discolored. 1) 0.0% per 100 parts by weight of the ingredients.
It is required to be in the range of 01 to 10 parts by weight,
This preferred range is 0.1 to 5 parts by weight.

In addition, the organic tin compound as component 5) in this composition is a known condensation reaction catalyst that has been conventionally used in this type of composition, and includes tin naphthenate, tin caprylate, and tin oleic acid. Tin carboxylates like tin, dibutyltin diacetate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin diralate, diphenyltin diacetate, dibutyltin oxide, dibutyltin dimethoxide, dibutylbis(triethoxysiloxy) soot, dibutyl An example is tin dibenzyl malate, but if this amount is too small, it will not function as a curing catalyst sufficiently and the curing time will become longer, and curing in the deeper parts of the rubber layer will be insufficient. If the amount is too large, the storage stability of this composition will deteriorate, so it is necessary to range from 0.01 to 10 parts by weight per 100 parts by weight of component 1), and this preferred range is 0.01 to 10 parts by weight.
The amount is 1 to 2 parts by weight.

Next, in the composition of the present invention, the organopolysiloxane containing at least one alkenyloxy group in one molecule as component 6) is contained in the diorganopolysiloxane as component 1) and the filler as component 2). This is to remove the alcohol generated by the reaction between the silanol groups and water contained in the 3) component and the alkoxysilane or its partial hydrolyzate. The addition of this alkenyloxysiloxane makes the composition of the invention more storage stable, since it reacts with this alcohol by its catalytic action in the presence of a guanidyl group-containing silane or siloxane as a component, converting it into an alkoxysilyl group. It is considered to be excellent. Since the reaction between this alkenyloxysiloxane and alcohol proceeds easily and stoichiometrically, the amount of addition of this alkenyloxysiloxane is such that the alkenyloxy group is equal to the alkenyloxy group/R
O) I≧1 may be satisfied, but if it is less than 0.1 part by weight per 100 parts of diorganopolysiloxane as a component, there is a risk that alcohol may remain; It is not necessary and it is economically disadvantageous, so 0.1~lo! The preferred range is 0.5 to 5Ii parts.

This alkenyloxy group-containing siloxane can be synthesized by addition reaction of vinyl group-terminated siloxitin and hydroalkenyloxysilane in the presence of a platinum-based catalyst; It can be easily obtained by simply mixing in the presence of the compound. Specifically, the alkenyloxy group-containing siloxanes include the following, OH
.

→-C-C)I2)2 H3 (0-C-CH,) 2 is exemplified.

The composition of the present invention can be obtained by mixing predetermined amounts of the above-mentioned components 1) to 6).
) A base compound is prepared by mixing the filler as the component 3), and then a predetermined amount of the alkoxysilane or the partial hydrolyzate of the component 2 and 4 are added to the compound as the component 3).
After adding the guanidyl group-containing silane or siloxane as the component 5) and the organotin compound as the component 5 and mixing them well under closed conditions, the alkenyloxysiloxane as the component 6) is added thereto to form an alcohol/alkenyloxysiloxane. After the reaction, the mixture may be thoroughly mixed and stirred under reduced pressure. In addition, the composition of the present invention obtained in this manner may optionally be added with a thixotropy imparting agent such as polyethylene glycol and its derivatives, a pigment, a dye, an antioxidant, an antioxidant, an antistatic agent, an antimony oxide, and a chloride. It is optional to add flame retardants such as paraffin, thermal conductivity improvers such as boron nitride, aluminum oxide, etc., and these include adhesion promoters, amino groups, epoxy groups, thiol groups, etc. Various conventionally known additives such as so-called carbon functional silanes, metal salts of carboxylic acids, and metal alcolades may be mixed, and for convenience during use, they may be mixed with hydrocarbon solvents such as toluene, petroleum ether, etc. It may also be diluted with ketones, esters, etc.

The composition of the present invention is a so-called RTV xyloquitin composition, which is stable under sealed conditions and quickly hardens into an elastic body due to moisture when exposed to air, and is particularly storage stable. It has excellent properties such as hardness and curing properties, so even if it is stored for 6 months, it will harden quickly when exposed to air, giving a cured product with excellent physical properties.
It does not emit toxic or corrosive gases when cured, nor does it cause rust on the treated surface.Furthermore, the cured product adheres well to various substrates, especially metal surfaces, making it particularly suitable for electrical and electronic components. In addition to being useful as an adhesive, it can also be used as a sealant, caulking agent, coating agent, water repellent agent, etc. for various base materials.
It is useful in that it can be widely used as a mold release treatment agent and as a fiber treatment agent.

Next, examples of the present invention will be given, in which parts are parts by weight and viscosity is a value measured at 25°C.

Example 1 Both ends of the molecular chain are blocked with hydroxyl groups, viscosity is 20.00
To 88 parts of 0 cP dimethylpolysiloxane, 9 parts of fume nX silica whose surface was treated with trimethylsilyl groups and 3 parts of fume-like silica whose surface was treated with cyclic dimethyl polysiloxane were added and mixed uniformly to form a base compound. Manufactured.

Next, 5 parts of methyltrimethoxysilane, 035 parts of γ-tetramethylguanidylpropyltrimethoxysilane and 0.2 parts of dibutyltin diphthoxide were added to 100 parts of this base compound, and after mixing under reduced pressure for 15 minutes, the formula shown by the formula was obtained. 2 parts of alkenyloxypolysiloxane (hereinafter abbreviated as alkenyloxypolysiloxane 2) was added thereto, and the mixture was mixed and stirred for 15 minutes under moisture-blocking conditions to prepare an RTV siloxane composition.

Next, this composition was extruded into a sheet with a thickness of 2 mm.
When exposed to air at 3°C and 55% RH, this product became dry to the touch in 5 minutes, and the physical properties of the cured product obtained by leaving this product in the same atmosphere for 7 days are shown in Table 1. By the way,
The physical properties of sheets with a thickness of 2III+ made from this composition left in a sealed container at a temperature of 70°C for 7 days and at 23°C for 6 months are as listed in Table 1. From this result, it was confirmed that this product had excellent storage stability.

(Note) Physical properties: Measured according to JIS-6301 method.

Examples 2 to 6, Comparative Examples 1 to 2 100 parts of the base compound produced in Example 1 was added with the second
The amounts of alkoxysilanes, guanidyl group-containing silanes, organotin compounds and siloxanes of the formula (
Below is alkenyloxypolysiloxane r! )
, a siloxane represented by the formula (hereinafter abbreviated as alkenyloxypolysiloxane III) or a siloxane represented by the formula (hereinafter abbreviated as alkenyloxypolysiloxane ■) was added and blended, and treated in the same manner as in Example 1 to obtain 7. A seed composition was prepared, and sheets with a thickness of 2 cm were made from this composition and those stored at 70°C for 7 days and at 23°C for 6 months, and these were stored in an atmosphere of 23°C and 55% RH. When the physical properties of the cured product at room temperature were examined, the results shown in Table 2 were obtained.

Procedural amendment (voluntary) 1. Display of the case: 1999 Patent Application No. 24909 2, Name of the invention: Room temperature curable organopolysiloxane composition 3, Person making the amendment: Relationship with the case: Patent applicant name: Shin-Etsu Chemical Co., Ltd. 4, Agent address: 103 Address: 4-chome, Nihonbashi Honmachi, Chuo-ku, Tokyo
103 4-5 Nihonbashi Honmachi, Chuo-ku, Tokyo, Subject of Amendment No. 4-11 No. 4-11 Scope of Claims a) Diorganopolysiloxane in which both ends of the molecular chain are blocked with a hydroxyl group or a di- or trialkoxy group
100 parts by weight, b) filler
1 to 400 parts by weight, C) General formula R'm5t(O
R'')4-m (here R1 is a monovalent hydrocarbon group, R2
is an alkyl group or an alkyl group substituted with an alkoxy group, m is O or 1) 1 to 50 parts by weight of an alkoxysilane or a partial hydrolyzate thereof, d) General formula (R32N) zC=N- (where R3 is hydrogen Silane or siloxane having at least one group represented by an atom or a monovalent hydrocarbon group in one molecule
0.01 to 10 parts by weight, e) 0.1 to 10 parts by weight of an organotin compound, and f) 0.5 to 10 parts by weight of an organopolysiloxane having at least one alkenyloxy group in one molecule. A room temperature curable organopolysiloxane composition characterized by:

Written amendment 1, Indication of the case 1999 Patent Application No. 24909 2, Name of the invention Room temperature curable organopolysiloxane composition 3, Person making the amendment Relationship to the case Patent applicant name (206) Shin-Etsu Chemical Co., Ltd. Company 4, agent address: 4-4-11-5, Nihonbashi Honmachi, Chuo-ku, Tokyo 103
Date of amendment order: “Spontaneous” 6. Target of amendment: ○ - Gokeya 7. Contents of amendment 1: Specification, page 5, line 5, page 6, line 13, page 1
Line 9, page 8, line 3, page 10, line 2, page 11, line 17
line, line 4 directly below line 13, page 14, line 4, page 15, line 2
Correct "■)" in line 7 of the same page, line 3 of page 16, line 2 of page 18, and line 4 of the same page to Ira) J.

2. Specification, page 5, line 7, page 6, line 14, page 1
Correct "2)" to "b)" in line 9, page 9, line 12, line 4 just below page 13, line 8 of page 15, and line 5 of page 18.

3. Specification, page 5, line 8, page 6, line 15, page 2
Line 0, page 11, line 9, page 12, line 3, page 10, line 2
Correct "3)" to "C)" in line 10, page 15, line 7, page 18, line 7.

4. Specification page 5, line 12, page 6, line 16, page 7, line 8, page 10, line 2, page 10, line 2, page 15, line 13, page 18 Correct "4)" in line 8 to rd)J.

5. Specification page 5, line 15, page 6, line 18, 14
Correct "5)" on page 7, line 18, page 18, line 9 to "e) J."

6. Amend "6)" to "f)" in page 5, line 16, page 7, line 6, page 15, line 5, page 18, line 2, and page 11, line 11 of the specification. do.

Claims (1)

[Scope of Claims] 1) 100 parts by weight of a diorganopolysiloxane whose molecular chain ends are blocked with hydroxyl or di- or trialkoxy groups, 2) 1 to 400 parts by weight of filler, 3) General formula R^1_mSi( OR^2)_4_-_m(
Here, R^1 is a monovalent hydrocarbon group, R^2 is an alkyl group or an alkyl group substituted with an alkoxy group, m is 0 or 1) 1 to 50 parts by weight of an alkoxysilane or a partial hydrolyzate thereof, 4) General formula (R^3_2N)_2C=N- (here R^
3 is a hydrogen atom or a monovalent hydrocarbon group)
0.01 to 10 parts by weight of a silane or siloxane having at least one group in the molecule; 5) 0.01 to 10 parts by weight of an organic tin compound; 6) 0.01 to 10 parts by weight of an organopolysiloxane having at least one alkenyloxy group in each molecule. 5 to 10 parts by weight of a room temperature curable organopolysiloxane composition.